Download the wrapper

The above command line will download and unpack the et-sdl-sound script.

Locate libSDL

For the next part you will need to know the location of the game installation (if not default) and the location of your 32bit libSDL.so
To find your 32bit libSDL:

$ locate libSDL

My 32bit library was located at /usr/lib/i386-linux-gnu/libSDL-1.2.so.0

Edit the script

$ nano et-sdl-sound

Uncomment the GAME_PATH line and edit to your installation path

GAME_PATH="$HOME/et/"

Uncomment the LIBSDL line and edit it to include the location of your 32bit libSDL library

LIBSDL="/usr/lib/i386-linux-gnu/libSDL-1.2.so.0"

Edit TMP_DIR from the default, my installation will not preload from /tmp this was the kicker and had me stumped for a while. As soon as the was changed to the installation directory it fired up with sound.

TMP_DIR="."

Save the file and execute the game with using the et-sdl-sound script in place of the standard executable

$ ./et-sdl-sound

Done

That's it, Enemy Territory fired up with sound after the steps above were completed